1. Field of the Invention
The present invention relates to a jacquard mechanism for controlling a shedding motion of warps set on a loom, particularly to an improvement of an electronic jacquard mechanism in which a solenoid of a needle selection device is directly operable by a command signal from a computer.
2. Description of the Related Art
In a traditional jacquard mechanism well-known in the art, specific dropper needles are selected at every pick of a weft in accordance with a position of a perforation on a pattern card.
In this jacequard mechanism, a large number of pattern cards, usually tens of thousands, are necessary for completing a pattern. These cards are connected one by one to form an endless belt and set in the mechanism so that they successively confront a selection device synchronously with a rotation of a main shaft. A considerable amount of space is needed for this. Also, the preparation of the pattern cards requires considerable time and labor. Further, setting and amending the cards are very troublesome. This problem is particularly, bothersome when just making samples of various weave patterns. It requires several months from the beginning of preparation of the pattern cards to the completion of the weaving on the loom.
Recently, to solve the problem, a so-called "electronic" jacquard mechanism utilizing a computer has been developed. In this mechanism, a magnetic tape or disc memories the pattern information and thus does away with the lengthy belt of pattern cards. Most such mechanisms further omit the dropper needles themselves to simplify the device. Instead, horizontal needles arranged in a final stage of the selection device are controlled by a solenoids.
This mechanism has, however, a serious drawback. Since the horizontal needles are urged to their waiting position by springs, an attactive force of at least 300 g.wt. is necessary to displace it or hold them in a selection position. This means the solnoids must be of a large capacity, therefore, large size. On the other hand, since a large number of horizontal needle, e.g., 1,000 to 2,000, are arranged in the jacquard mechanism for controlling the warps, the pitch between adjacent needles must be as small as possible to keep the overall installation small. Since the solenoids are large in size, however, they cannot be arranged at a small pitch corresponding to that of the horizontal needles. To solve this problem, the solenoids are disposed apart from the horizontal needles. The solenoids and needles are connected by flexible components such as steel wires or synthetic fiber cords. Due to repeated stress, however, the flexible components tend to stretch with the time, resulting in indefinite displacement of the horizontal needles. In the worst case, the flexible components break due to material fatigue.
In view of this drawback, the present inventors previously proposed a system in Japanese Unexamined Utility Model Publication (Kokai) Nos. 56-107878, 57-18680, 57-34587, 57-34973, and 58-87884 in which periodically reciprocating dropper needles are selectively attracted by corresponding solenoids. Because a much smaller force is required for operating dropper needles compared to horizontal needles in conventional mechanisms, solenoids of a smaller capacity and, therefore, a smaller size are sufficient and the compactness of the jacquard mechanism can be maintained without problem. The present invention is an improvement of this system.